How to improve a JBL 2431H 1.5"? - diyAudio
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Old 24th August 2015, 02:45 PM   #1
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Default How to improve a JBL 2431H 1.5"?

Hi all,

I would like to improve a pair of JBL 2431H (Neodynium 1.5" HF driver).

It is an interesting, recent driver (low weight 2.7lbs, 1.95T induction), which has replaced ceramic magnet drivers like the 2452.
But its frequency response is not so flat above 10kHz.
Here is its frequency response mesured on a plane wave tube:

Click the image to open in full size.

Should it be possible to change its diaphragm for a better one (like the 2452's one for example)? or anyway to improve this 2431?

Thanks in advance,

Regards
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Old 24th August 2015, 03:27 PM   #2
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Quote:
Originally Posted by Massilia View Post
Should it be possible to change its diaphragm for a better one (like the 2452's one for example)? or anyway to improve this 2431?

Thanks in advance,

Regards
Massilia,

Pretty much all 3" diaphragm drivers will have some VHF peaks and dips.
The 2452 diaphragm is all titanium, not likely to be an improvement regarding smooth response. The Mylar surround on the 2431 probably makes it as smooth as you will get from JBL.

I would suggest using parametric EQ to take out the 2431's peak around 14,500 Hz, but first measure yours on whatever horn you use to see if it has the same peak as "Line Std #33 on a 2" tube using a 1.5" adapter".

Art
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Old 24th August 2015, 05:24 PM   #3
Flaesh is offline Flaesh  Russian Federation
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2452 is 4" neo with ribbed phragm, 2452-SL with aquaplased phragm.
Pics and measurements: 2450 Dia - Page 7
Don't know\remember about SL or Be phragms for 2431.
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Last edited by Flaesh; 24th August 2015 at 05:38 PM.
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Old 24th August 2015, 10:31 PM   #4
djk is offline djk
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A 2435 diaphragm will fit.

Click the image to open in full size.
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Old 25th August 2015, 02:30 PM   #5
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Thank you very much for your responses.

I tried to make an EQ (using the XTA DP226 active filter) on my 2431 mounted on a JBL PT horn... the response above 10kHz was very bad before. But despite this correction, the sound quality remained rather poor...

For the moment I have replaced the 2431 drivers by the 2452 (thanks for the precision that it uses a 4" diaphragm), its sounds a lot better and needs a raisonnable EQ to be flattened. The inconvenient is that the weight is considerably higher.

So I note the possibility to use the 2435 diaphragm, which seems indeed more flat. Do someone know if 2431 uses ferrofluid, and if it is not too difficult to change the diaphragm for a non-expert?
And where to buy the 2435 diaphragm?

Thanks in advance,

Regards
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Old 25th August 2015, 02:49 PM   #6
Flaesh is offline Flaesh  Russian Federation
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iirc 2435 diaphragm is Be about $700+\ea on ebay
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Old 27th August 2015, 12:30 PM   #7
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Thank. Others suppliers are possible among the recone-kit specialists. About 700$/part indeed, plus customs taxes from US to France, Europe...
Anyway; can someone tell me if 2431H uses ferrofluid, and if it is difficult to exchange the diaphragm for a non-specialist ?

This Beryllium diaphragm seems very interesting (very low weight, higher mass-breakpoint) for an audiophile usage.

Thanks in advance!
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Old 28th August 2015, 04:05 AM   #8
GM is offline GM  United States
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This says 'yes', providing it in a replacement kit: Amazon.com: JBL Factory Speaker Replacement Diaphragm D8R2431, 2431H, 339894-002X, and many others: Electronics

Do not know anything about actually doing a replacement.

Yes, ideally Be is the way to go for HIFI if no super tweeter horn is used.

GM
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Old 28th August 2015, 06:58 AM   #9
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Thank you GM.
I asked also to "the Speaker Exchange"; they have a response from JBL saying that:

"
As far as I know the primary difference between these is beryllium vs. titanium diaphragm membranes. I have heard of this being done in the field but it is not something that we recommend in any of our documentation.

-> The diaphragm exchange from 2431 to 2435 seems possible but not guaranteed.

And they confirm me that it uses ferrofluid. Problem, I don't know how removing it and correctly put it in with the new diaphragm...
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Old 28th August 2015, 08:04 AM   #10
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Lansing Heritage Forums may be useful
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